I just installed version 13 x64 and see now that the fonts in the application don't adhere to windows font size increase feature.

I run the new 4k monitors and as such have the font size increased by 125%. The fonts in the menu bar (file, edit, view etc) have all increased in size accordingly, however, the fonts in the workspace pane, file tab text and the Editor and Preview tabs are their default size (not increased by 125%.

Is this something I can change in a setting file some where or is this an issue in the application itself?

If you want rescale to appear correct, try Win 8.1 or higher.